| This dissertation, divided into three separate sections, investigates the paleoenviromnental history of James and Granite lakes, by examining the sedimentary, hydrogeochemical and micropaleontological history found in the lake sediments.; Chapter One introduces this dissertation and leads to the field methods outlined in Chapter Two. Chapter Three investigates the Holocene sedimentary history of the area, outlining changes in climate that occurred after the retreat of the Laurentide Ice Sheet more than 10,800 +/- 220 yr. BP. As indicated by the sediment types found, three paleoclimatic regimes existed during the Holocene. A glacial fluvial (sand) regime existed until 10,800 +/- 220 yr. BP as the Laurentide Ice Sheet retreated from the area. This was followed by an ice-marginal glacial lake regime, which deposited silts and clays from 10,800 to 10,700 yr BP. Finally, from 10,700 yr. BP to the present a mesotrophic lacustrine environment prevailed and has deposited 3.5 m of gyttja, the mass accumulation of which mirrors the relative water level of the system.; The geochemistry of the bottom sediment, and lake waters indicate that two chemically separate water types, carbonate poor, Na-K waters enter James Lake from the north and mix with anthropogenic influenced waters in the south. These anthropogenically influenced waters are Mg-SO4 rich and found adjacent to the abandoned Northland Pyrite Mine waste rock pile on the southwestern shore of James Lake. Although an inlet stream to Granite Lake is adjacent to the waste rock pile, metals dissolving from the waste rock generally precipitate before the waters reach Granite Lake to the south. Indications are that the James and Granite Lake system, as a whole, has been exposed to these metals since 8400 yr. BP.; Palynology indicates that the forest in the area since the Holocene warm period has been a mixed Great-Lakes St. Lawrence type. The James and Granite lakes system has cycles of high and low water, as shown by cyclic high and low diversity populations of arcellaceans. Within these cycles, the high nutrient indicator Cucurbitella tricuspis, found in conjunction with the algae Pediastrum indicates generally eutrophic conditions in the lakes. |
